To observe living biological systems using a light-optical microscope, it is very important to keep photo-induced damage to a specimen as low as possible. For this purpose, the concept of illumination using a light sheet in the detection plane of the microscope has been developed. This makes possible a microscope which uses selective plane illumination microscopy (SPIM). In this case, the propagation direction of the illuminating light is perpendicular to the detection direction, it being possible for said light to be coupled into the specimen volume via illumination optics, for example a second illumination lens, which is perpendicular to the detection lens. In this case, shading effects may be caused by the specimen. It is therefore expedient to illuminate the specimen from different directions in order to overcome this problem. This has hitherto been carried out in chronological succession and/or with a high level of mechanical complexity. The microscopic specimen preparation is heavily influenced by this, and is often not compatible with conventional light-optical microscopy.
DE 10 2004 034 957 A1 discloses an optical arrangement in a microscope, in which an illuminating light beam extending on an illumination side is generated by means of an illumination device. The illuminating light beam is split into two partial beams Ls1 and Ls2 by means of a splitting device T. The partial beams are reflected into an illumination region by means of a mirror arrangement R1, R2 for plane illumination of a specimen.
Specifically, the two partial beams Ls1 and Ls2 are guided laterally past a lens Lz through light guides LF formed in a housing H and are then reflected into the illumination region towards the specimen via the mirror arrangement. The lens Lz is arranged inside the housing H, such that the lens dimensions need to be adjusted to the dimensions of the housing, or vice versa. This ultimately results in a complex construction having light guides LF formed in the housing H and a lens adjusted to fit therein. It is often not possible to freely select the lens owing to the dimensional constraints imposed by the housing. The lens which is adjusted to fit into the housing detects light signals from the illumination side.
Furthermore, DE 102 57 423 A1 discloses an optical arrangement in a microscope, using which plane illumination of a specimen is likewise possible. Specifically, the known arrangement comprises two mutually perpendicular lenses for illumination on one hand and detection on the other. An arrangement of this type requires a very specifically adapted specimen mount, and can often only be produced with difficulty in terms of its geometry and structure.